This invention relates to fasteners for securing insulation to walls. More particularly, this invention pertains to improved fasteners which facilitate the securing of relatively thick insulation to walls and which also facilitate the securing of insulation to walls which are relatively hard and difficult to penetrate.
U.S. Pat. No. 3,401,494 relates to a method of securing sheets of insulating polystyrene foam between gypsum panels and concrete walls and to the resultant composite wall structure. The method and resultant wall structure utilize metal fasteners which, in preferred form, are channel shaped and have serrated legs depending from an elongated web. The fasteners are pressed into the polystyrene foam and the resultant assembly is secured to the concrete wall by nails or pins driven through the fastener and polystyrene and into the concrete wall. The fastener allows the foam to be secured to the wall without appreciable deformation of the material. Gypsum paneling is then attached to the metal fastener by the use of regular screws employed for such purpose.
Although the fasteners described in the patent provide advantages and have proven to be commercially useful, they do not provide an altogether satisfactory means of attaching rigid or semi-rigid insulation members to a supporting structure. In this regard, it should be recognized that the polystyrene boards, as well as most other types of rigid or semi-rigid insulation members which can be used in conjunction with the fasteners, are formed of relatively soft materials which do not provide support to the pin or nail as it is being driven through the insulation member and into the supporting wall. This lack of lateral support alongthe length of the nail as a driving force is being applied can result in bending or buckling of the nail. In addition, since the nail is also unsupported at the intended point of entry into the wall, there is a tendency for the nail to deflect or "skip" on the surface of the wall and, thus, to contact the wall at an oblique angle rather than at the desired 90.degree. angle. As a result, reliable and consistent penetration of the nail into the wall are not always achieved.
The severity of the above-described difficulties generally increases with increasing insulation thickness, inasmuch as the longer nails which are required have a greater tendency to bend or buckle. The difficulties are also more severe and occur with greater frequency where the supporting wall is hard and difficult to penetrate. For example, in retrofitting old concrete walls, compressive strengths of 5000 psi or greater can be encountered. With such walls, satisfactory penetration with unsupported fastening nails can be particularly difficult to achieve.